A gradient reversed phase stability-indicating high-performance liquid chromatographic (HPLC) assay method was developed and validated for quantitative determination of Epinastine hydrochloride in bulk drugs. A gradient reversed phase HPLC method was developed to separate the drug from the degradation products, using an Kromasil C18 (250 x 4.6) mm, 5 u column and the mobile phase containing 0.01 M KH2PO4 and buffer pH 5.2 with phosphoric acid and acetonitrile. The detection was carried out at wavelength 254 nm. The Epinastine hydrochloride was subjected to stress conditions of hydrolysis (acid, base), oxidation (30% H2O2) and thermal degradation. The degradation was observed for Epinastine hydrochloride in acid, base and 30% H2O2 and negligible degradation observed in thermal hydrolysis. The mass balance was close to 100 in all the stress conditions. The developed method was validated with respect to linearity, accuracy (recovery), precision, system suitability, selectivity, robustness prove the stability indicating ability of the method.